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What is fork offset?

By Bruce Lin


Dropper posts, extra-long reach, coil shocks, 29” wheels, tire inserts — I’ve always been quick to try any tech that claimed to improve downhill performance. Mountain bikes equipped with reduced-offset suspension forks started getting buzz a couple of years ago. Hungry for more speed, I was quick to buy a new fork and test it out. Was it good? Yes. Did it change my world? Well, not quite.

I’ve studied the science and switched back and forth between reduced offset and “traditional” 51mm offset 29er forks on my own bikes. If you're interested in trying a reduced offset fork, this article is for you. Let's find out how fork offset affects your ride, why reduced-offset forks are becoming popular, and how riding a reduced offset fork feels to the average Joe (me).

What is fork offset?

Fork offset is the distance between the front axle and the steering axis of the fork.

mountain bike mtb reduced fork offsetThe diagram above shows how the front axle is offset so it is forward of the steering axis. This offset is measured in millimeters. Its purpose is to adjust the amount of 'trail' in the steering geometry. For 29" bikes, the 51mm offset fork has been the standard for nearly a decade. 

What is trail?

If you draw a line through the steering axis to the ground (as in the diagram above), trail is the distance from that point to where the front wheel touches the ground.

Trail is what makes the bike's front wheel self-straighten when it is moving forward. Think of the wheels of a shopping cart. They want to straighten when you push the cart forward. This same phenomenon occurs on your bike. It helps you stay upright when riding on two wheels. 

Increasing trail improves straight-line stability. The front wheel feels harder to turn but also harder to knock off line.

Decreasing trail improves agility. The front wheel feels easier to turn and it can make a bike feel more nimble.

Trail on a mountain bike is affected by three factors: fork offset, wheel size, and head angle.

Reducing fork offset increases trail. Increasing fork offset reduces trail.

Larger wheels increase trail. With a larger wheel (e.g., a 29” wheel) the axle is higher off the ground compared to a smaller wheel. If you draw a line through the steering axis to the ground, it intersects the ground farther forward of the axle, increasing trail.

Slacker head tube angles increase trail. With a slacker head angle, the intersection of the steering axis and the ground is farther forward of the axle, increasing trail.

Increasing or decreasing trail too much makes a bike difficult to control. For mountain bikes, the sweet spot that provides a good balance between stability and agility is around 80-100mm of trail. Many mid-travel bikes settle near 90mm with a 51mm offset fork.

Why did 51mm offset forks become standard for 29” mountain bikes?

When 29ers first appeared, they didn’t catch on right away. 29ers had more trail due to the larger wheels and felt hard to turn compared to traditional 26" bikes. Mountain biking pioneer, Gary Fisher, found the handling of 29ers to be too slow and ponderous. He wanted to improve it with his new line of 29er mountain bikes in 2009/2010. These bikes introduced what Gary Fisher called “Genesis 2 (G2) Geometry.”

Gary Fisher G2 fork geometryA 2009 Gary Fisher Superfly with a G2 (note the 'G2" on the fork lower) 51mm offset fork.

The defining feature of G2 Geometry was a fork with the offset increased to 51mm. Early 29er forks used the same offset as 26” forks (around the 40mm range) which contributed to the high trail numbers. 

Mountain biking legend and product tester for Trek’s R&D department, Travis Brown, helped refine the offset used in Gary Fisher G2 Geometry bikes.

“We were trying to prove the credibility of 29ers and a big roadblock was the trail numbers,” says Brown. “People thought the head tube needed to be steep to maintain the trail figure we had already established for 26” bikes. This steep head angle was really preventing the category from moving forward. ”

Bike designers in the early 2000s tried making 29er head angles steeper to reduce trail so their bikes would have quick handling similar to 26” mountain bikes. This approach worked, but it sacrificed downhill performance. Steep headtubes made these bikes less stable. A lot of riders went over the bars on these bikes. 

“We decided instead to engage in the offset variable because it allowed us to use a slacker head tube angle and still maintain a trail figure that was acceptable,” Brown explains. “You don’t lose any of the benefits a slack head tube provides for fast descending, but you still have a low trail number for handling tight corners.”

Why are bike designers now reducing fork offset?

Stability is the new prime goal of modern trail and enduro mountain bikes. To provide this stability, geometry has evolved so that new bikes have longer reaches, shorter stems, and slacker head angles. This gives riders great control and confidence when descending fast on steep terrain.

But the disadvantage of this new-school geometry is that the front wheel gets pushed farther forward of the rider. Because the front wheel is now so far in front of the bike’s center of gravity, it’s harder to maneuver in tight corners and get weight on the front wheel for traction.

mtb cornering position
“You need to learn to ride with your weight shifted more toward the front of the bike,” explains Isreal Romero of Mondraker bikes. Mondraker helped drive the development of longer bikes, and riders have since had to adapt.

“You have to be more aggressive with your weight positioning and actively push forward," Romero says. "This way you'll have more confidence in your front tire grip. The more aggressive you are and the faster you’ll go, the better the bike will ride. It might take a couple of rides, but once you get used to it, it will be natural.”

When things get steep and hairy, our instinct is to lean back, away from danger. But with a long and slack bike, you need to do the opposite and lean forward to maintain traction. It takes a lot more commitment, and these bikes will punish timid riders with a sudden loss of traction or by running wide.

Reduced-offset forks have promised to remedy this needy bike behavior. Reducing offset brings the front axle back closer to the rider. In theory, this should keep the wheelbase from getting too long for tight corners and make it easier for the rider to get weight on the front wheel.

Transition Sentinel SBG Speed Balanced Geometry reduced offset forkA Transition Sentinel with a reduced offset fork.

Transition Bikes was one of the first major brands to tout the advantages of reduced offset forks with its “Speed Balanced Geometry (SBG),” which used shorter 42-44mm offset forks. Competitors followed suit and now several popular bikes come from the factory equipped with reduced offset forks.

Travis Brown has performed testing for Trek that supports the performance claims of these new reduced offset forks. 

“When we did offset testing on forks, we wrapped the crowns so the field testers couldn’t tell what fork they were riding,” Brown says. “We do everything we can to prevent confirmation bias. We have some ongoing experiments with our riders now where they have been trending back toward shorter offsets."

Travis Brown reduced fork offset Travis Brown bike testing in Sedona, AZ.

“Now that the appetite for slack head angles has changed significantly for 29” bikes, we’re really reevaluating what the appropriate offset is," Brown says. "Sometimes I do think modern geometry has gone a bit too far with long reaches and slack head angles. Those bikes are very stable, but they have a narrow performance window. You have to ride them on really steep and fast terrain and be very aggressive to get the most out of them.

“But we’re discovering that a reduced offset fork can reign in these extreme traits a bit. It's easier to find traction in tight corners and through a bigger range of speeds.”

We know that trail is affected by offset, wheel size, and head angle. A 29” bike with a slack head angle already has a large amount of trail. So how can reducing fork offset and increasing trail improve cornering? On paper, it should make a bike harder to turn.

But, remember that riders need to shift more weight forward in order to corner well on long and slack bikes. Even though the actual steering geometry is more resistant to turning, reducing offset and increasing trail achieves the same result as the rider positioning their body farther forward. You are, in effect, achieving a better position and weight distribution for good cornering through the geometry. Because the front wheel naturally maintains traction, it feels easier to attack corners.

This is something motocross riders already discovered years ago. Reducing fork offset had the same effect as moving the engine forward in the frame. You have more stability, but the steering feels better because more of the bike’s weight is biased forward, keeping the front wheel planted. As with suspension, wide handlebars, and mullet wheel sizing, the mountain bike industry continues to apply lessons already learned with motorbikes.

Reduced offset forks mtbThere’s an additional benefit too. Trail shortens as a fork compresses (the head angle steepens). This makes a bike less stable when it’s deep in its travel. Because a reduced offset fork has more trail at full extension, it has more trail at full compression too. More stability deep in the travel is always a good trait to have for hard-hitting enduro and downhill bikes.

My experience

There are several trail and enduro bikes that come from the manufacturer with reduced offset forks. 2018+ Transition SBG, 2019+ Yeti SB-series, and 2020+ Santa Cruz 29er bikes are great examples of bikes designed around reduced 42-44mm offset forks. Reduced offset is less common for 27.5” bikes (for now) but some brands like Transition and Yeti offer 27.5” models using reduced 37mm offset forks (27.5” bikes traditionally use 44-46mm offset forks).

If you want to purchase an aftermarket fork to experiment with, FOX produces reduced 44m offset forks and RockShox produces 42mm offset forks for 29” wheels; 37mm offset forks are available for 27.5” wheels.

Fox 36 hightower reduced offset fork mtbThe first reduced-offset fork I tried was an aftermarket 44mm offset FOX 36. I purchased it for my 2018 Santa Cruz Hightower LT. While waiting for it to ship, I dreamed about how this fork would turn me into a cornering machine and help me destroy all my Strava PRs.

After installing the fork, I was in for a rude awakening. I remember dropping into an extremely steep and technical local trail and feeling like I was struggling to dodge rocks and keep things under control. The subtle change in geometry made my timing feel slightly off. That first impression stuck with me.

I got used to it after a few runs and the bike soon felt normal. I rode the new fork for a total of eight months. Was I faster? My lackluster Strava times say not by much. Reducing the offset of my fork wasn’t a magic pill. If it improved my speed, it was marginal.

Even though I wasn't smashing Strava KOMs, the claimed traction benefits were still appreciable. I felt more stable and planted when I turned into corners. I’ve never been good at 180 degree turns, and the reduced offset fork made me feel just a little more comfortable. In time, I became less scared of the front wheel washing and this helped me focus more on my positioning and technique through corners.

Practicing my cornering technique over the last couple of seasons has made the biggest difference in my overall speed. Perhaps the little extra traction I felt with the reduced-offset fork sped up the process. I think it can be a useful tool for improving confidence and honing your technique. (If you really want to improve your cornering, check out these tips I got from world-renowned mountain bike coach, Lee McCormack.)

So, switching to a reduced offset fork isn't going to be life-changing, but it’s still nice to have. What’s my recommendation? If you’re buying a new bike and cornering is your weakness, choosing a reduced offset fork can help. If you’re trying to race enduro or downhill competitively, a reduced offset fork can give you a slight edge. But if you don’t have a reduced offset fork on your bike right now, don’t worry too much about it.

On my last few bikes, I’ve swapped forks out several times between reduced offset and 51mm offset forks. Each time I get used to the new offset within a ride or two. In my experience, you simply adapt to whatever you’re using. If you practice enough with whatever you have, you will get faster. That's the truth. 

My current enduro bike has a 51mm offset fork because The Pro’s Closet offered them at a great discount. I’m used to how it handles now, and I see no reason to change it yet. I'm pretty much sold on the idea of reduced offset forks, but since it's not life-changing, there's no need to spend money if your current set-up works fine. If my current fork gets damaged, or I decide to buy a new bike, I will choose a 42mm or 44mm offset fork just to give myself a little mental boost.

No matter what fork I'm on though, it will still be fun to ride!


Do you ride a reduced offset fork? What’s your experience been? Let us know in the comments!


  • I have a trek dualsport 2 with a 63mm suspension fork 38mm offset. I mainly ride on ride city roads. I would like to change to a suspension corrected rigid fork , but want to retain stability. Most i see are 42mm to 45mm offset ? Whats your opinion on how far up can i go ?

    M M on

  • I have a 2021 Specialized Fuse Comp 29er, and the 130mm RS Recon fork is not adequate enough for me. Specialized website says the rake is 46mm. I have been looking at new forks in the 140mm-150mm range, and am not sure whether I should go 44mm since it is closer to 46mm, or go 51mm?

    In your experience for a hardtail, what do you suggest?

    I just do not want to make that kind of investment and really regret it.


    Danny C on

  • Hey Marcus,
    Fork offset is essentially independent of frame sizing. So, yes, you might have trouble if a frame is slightly oversized for you, but that would be unrelated to the fork’s offset. The key is finding a bike with the right combination of reach and stack for your body’s proportions.

    Spencer Powlison on

  • How does frame size factor into all of this if at all. I think most people will always up size if between sizes. Won’t that essentially make it harder to weight the front end as opposed to to downsizing?

    Marcus Valentine on

  • Hi Cody,

    First, no you didn’t screw up your bike. 44mm is the traditional rake for 27.5" forks (short is ~37mm). It’s likely your Carbine came with that originally. What you’re probably noticing is the slacker angles due to a longer fork. Also, the 38 is much stiffer and heavier than the Pike. I’d suggest putting more rides in before making a judgment. Our bodies are pretty adaptable and 10mm is not a massive change so you might get used to it very quickly. Also, offset and rake refer to the same thing ;). Hope that helps!

    Bruce Lin on

  • Sorry meant 44mm offset not rake

    Cody Payne on

  • Hi Bruce,
    I just swapped from a Pike 160 to a Fox 38 170 w/ 44mm rake. Now the steering feels odd as if the front wheel is harder to turn? And feels almost like it is tramlining when I take my hands off the bars.

    Did I screw up my bike? (2015 Intense Carbine 27.5)

    Thank you!

    Cody on

  • Hey Adam, typically it’s best to run what the manufacturer specs for a fork offset, given that they design the bike holistically. That said, A shorter fork offset might not significantly change your bike, and if it did, it would likely give it more straight-line stability.

    Spencer Powlison on

  • Great article very interesting read, could you please advise I have a 2020 commencal meta am 29 with a 51 mil offset I’m thinking of upgrading the fork will it be possible to put a 44 mil offset on this will it make alot of difference? Look forward to your reply cheers adam

    Adam Webster on

  • I have Santacruz Bronson 2 / 27.5 / Head Tube Angle 66 °. I want to buy a new fork Fox 36 factory 160mm. What offset do you recommend? 37mm or 44mm. According to the calculator 37mm – 92mm trail, 44mm – 85mm trail.
    Thank you for your response

    Juraj on

  • Hi .ive a specialized kenevo..with 44mm ofset 180mm forks… Just fitted a set of 190mm forks with. 38mm offset…had a few slips today where nearly lost front end…
    Should i reduce travel back to 180mm. Or ant other ideas

    Nigel Dix on

  • Hey Tony, thanks for the question. 
    In short, yes, getting a reduced offset fork should make your bike feel more stable. It might also make it feel easier to weight the front wheel and get traction.Stability is a combo of a lot of factors – wheelbase, head angle, reach, bottom bracket height, stem length, bar width, and trail/fork offset. Changing one affects the others. 
    If you’re already thinking about buying a reduced offset fork, you could go all in and get a bigger 170mm travel fork too. This will lengthen your wheelbase and slack out your head angle. I over-fork all of my bikes for the ultra-steep stuff I ride in Colorado. If you want to get super nerdy, offset bushings in the shock or a cascade linkage will lower your bottom bracket and slack out your head angle, but I wouldn’t mess with that stuff unless you really know what you want. I say big/reduce offset forks are the first step. 
    Hope that helps.

    Bruce Lin on

  • Hi Bruce

    I have a 21 Santa Cruz Bronson V3 and I am finding the handling very twitchy and I’m not liking it. When the bike arrived I reduced stem length from 50mm to 40mm, removed all stem spacers bar one 10mm and installed a 35mm carbon riser bar. I just don’t feel comfortable on the bike on fast, steep descents, so was thinking a switch to 37mm offset might make it a bit more stable?



    Tony Whelan on

  • Thanks for the question, Jared. Unless you’re doing a lot of gravel and fireroad miles (where the shorter offset might feel a bit slow and lazy) I say you’ll be fine with a 44mm offset fork on any trail. Also, complete Scout builds come from the factory with a reduced offset fork.

    Bruce Lin on

  • Hey man, I am currently planning my hardtail build, and using the Nukeproof Scout as a platform. Not near any mountains or large downhill areas so the 44 would be a good choice eh?

    Jared on

  • These comments, as shown by the photos, are all directed toward people interested primarily in rushing downhill on winding dirt trails, jumping into the air whenever possible.

    Which ignores the large demographic of people who want long stable off-road touring bicycles instead. Maybe Pro Closet should also write reviews relevant to people other than downhill schussboomers?

    Jack Kessler on

  • GM Bruce, have a quick question: Current offset on my bike is 42 I want to switch to a 44 offset with a newer Fox 34 fork. Currently am running a RS judy 130mm travel, with the Fox I will have 140mm or travel. would you recommend going with the Fox?

    Gurpreet s Gill on

  • Hello, I have a 2020 commencal am 29 with a 51 mil offset fork is it possible to put a 44 mil fork on & what difference should I expect?

    Adam Webster on

  • Hey Vinicius, 
    Of your two options, I’d personally choose a 160mm 27.5 fork. I’ve gone to forks with 20mm more travel on several bikes now, so I have more confidence that combo will handle well. 

    I haven’t experimented enough with mullets yet, and when I have it’s been putting a 27.5 on the back of a 29er bike. But hey, I don’t think it’ll ruin anything, so if you’re leaning that way (mullets are hot right now) and feeling adventurous then maybe go for it. A 29er fork might be easier to resell later too if you don’t like it. 

    Bruce Lin on

  • Hey Bruce,

    I have a Cannondale Trigger 27.5 2015 with a lefty fork with 50mm offset. How would be if put a fork with reduced offset on it using one of the two following ideas.

    1 . Using a 27.5 fork with 37mm offset and increasing the fork travel from 140 to 160mm
    2. Using a 29 fork with 44mm offset and increasing the fork travel from 140 to 150mm turning my 650b rig into a mullet bike

    Just thinking about the pros and cons about doing that, can you help me to figure out?

    Vinicius on

  • Hi Doaner,

    Your bike will be fine with a 51mm offset. 29ers have used 51mm for years and it’s what I still use. It won’t affect the feeling of “slackness,” just how responsive your bike feels when turning into a corner. Think about it this way. Go shorter offset for more straight-line stability, and longer offset for a more nimble feeling. I wouldn’t stress too much about it though. Whatever’s on the bike you’ll get used to. The difference isn’t massive. 

    Bruce Lin on

  • I have a Santa Cruz super light now and the head tube angle is 70.2 , I have a 44mm rake now. I was thinking I would go with a 51 mm rake fork. Will this be good? I would like to know if it’s going to feel slack and mess with me ride. Tire size is 29 with 2.3 wide tires .
    Thanks for your input .
    Rubber side down.

    Doaner on

  • Awesome article, really puts it into clear perspective, thanks. On my 29er XC bike with 70deg HT the 51mm works well but building a Commencal HT with 65deg HT, XL frame so it’s pretty darn long already so 42mm RS Pike will be sweet. Thanks for confirming this for me!

    Andrew on

  • On my Whyte S150 CRS 29er which came with a 44mm offset pike, I have noticed that when you do drop off at speed to flat that there is less slowdown/stutter caused at impact compared to my 51mm offset fox 34 fork. It could just be the fork characteristics but I’ve always assumed it was the offset. The only other thing I notice is the 44mm is more stable no handed and the 51mm needs a bit more steering correction. My gut feel from riding other bikes is that 44mm is better for anything below 67 degree head angle and the 51 is better for steeper head angles like my 68.5 degree cannondale trigger. Which would make sense that it only came into play as trail bikes got lower, longer slacker.

    StephenD on

  • Hi John,

    You will be 100% fine with the 51mm offset fork. Your Giant Talon most likely came stock with a 51mm offset fork. Even if it somehow didn’t (unlikely), your bike’s handling won’t be massively changed. 

    Bruce Lin on

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